Smoke detector beeping even without batteries! Help!

[Arcadia]

Our smoke detector started randomly beeping last night about midnight so I immediately changed the battery, but it's still beeping! I'm pretty certain it's not hooked up to mains power or the security system.

I took out the battery to clean it and it beeped even without the bloody battery! I gave it a dust but couldn't get all the dust off.

Is it just old? I tried taking the battery out and pressing the test button to reset it (as per googles instructions) but nothing happened.

It's driving me insane and I worry about it not working.

[Phteven]

I'd replace it. They're not very expensive or difficult to install.

[Chocaholic]

How old is it? They have an expiry date just like batteries.

[LimeSlice]

Are you sure it isn't hardwired? How old is your house?

[JLeigh29]

Our old one beeped even without batteries...I always thought it was a safety thing that it did that to remind you there were no batteries...?!

Def get a new one.

[Arcadia]

Thanks everyone. House is old (1890s) and renovated most recently late-90s. We moved in here in 2009/10. I replace the battery regularly, but I think the unit is prob old.

Grrrr to the beeping. I love smoke detectors though, so off to the hardware shop I go!